载体两性电解质修饰对固定化γ-谷氨酰转肽酶pH耐受性和催化活性的影响

Improving p H tolerance and catalytic properties of immobilizedγ-glutamyltranspeptidase by coated with carrier ampholyte

针对γ-谷氨酰转肽酶（GGT）p H耐受性差的缺陷,首先以硅烷化改性的介孔氧化钛晶须（s MTw）为载体对重组枯草芽胞杆菌GGT进行固定化,再以p H 8.0-10.5的载体两性电解质Pharmalyte（CA,p H 8.0-10.5）对其进行后修饰,得到固定化酶s MTw-GGT-CA。结果发现：s MTw-GGT-CA的p H耐受性较游离酶明显提高,可在p H 6.0-11.0范围内保持稳定的催化活性。同时,s MTw-GGT-CA的热稳定性也较游离酶有所提高,其最适作用温度为50℃左右,热失活反应活化能Ed为49.88 k J/mol。s MTw-GGT-CA对γ-谷氨酰对硝基苯胺（Gp NA）的亲和力常数Km为0.579 mmol/L,与游离酶相近。

In order to improve pH tolerance of γ-glutamyltranspeptidase （ GGT ） , recombinant γ-glutamyltranspeptidase （ GGT ） from Bacillus subtilis was immobilized onto silylated mesoporous TiO2 whiskers（sMTw）. Then it was modified with carrier ampholyte（Pharmalyte pH 8. 0 to 10. 5,CA）. The pH tolerance of modified immobilized enzyme（sMTw-GGT-CA）was greatly improved in comparing with the free GGT, stable under pH ranging from 6. 0 to 11. 0. Furthermore, the thermal stability of sMTw-GGT-CA was also higher than that of the free GGT, with optimal temperature as high as 50 ℃. The thermal inactivation energy（ Ed ） of MTwA-GGT-CA was calculated to be 49. 88 kJ/mol. Also,the Km of MTwA-GGT？CA towards GpNA was 0. 579 mmol/L, very close to that of the free GGT.